Troubleshooting a Local License Manager

For common errors associated with a local license manager, please see the following Knowledge Base articles:

Using ERDAS IMAGINE, how do I correct the error message "Cannot find valid license information needed for IMAGINE Essentials"?

Installing ERDAS IMAGINE 9.x, how do I set up the local license for laptop or home computer?

How do I update the license file for ERDAS IMAGINE?

For ArcGIS or IMAGINE, why do I need a sentinel key?

How do I install ArcGIS Desktop 9.2 using a sentinel key?

How do I install the ArcGIS 9.x License Manager?

Running ArcGIS, if I receive the error message "Cannot find SERVER hostname in network database", what should I do?

Using ArcGIS, how do I correct the error "Hostname entered is invalid"?